Abstract This application seeks to renew an NICHD-sponsored National Research Service Award T32 that supports fellowship training in the Department of Pediatrics at the Children's Hospital of Philadelphia (CHOP) and the Perelman School of Medicine at the University of Pennsylvania (Penn). The long-term objective of the training program is to foster the development of pediatric investigators who are prepared to pursue independent academic careers examining important issues relevant to health and disease in children. The program will exploit the rich research and training resources at CHOP and Penn, including a cadre of faculty mentors in the Department of Pediatrics and other departments who are performing rigorous science in areas germaine to pediatrics, have a strong record of successful mentoring and collaboration, and have a strong record of extramural funding. Four trainees will be supported each year and will be drawn from subspecialty fellows in the Department of Pediatrics, with particular emphasis on recruitment of women, underrepresented minorities, individuals with disabilities, and other disadvantaged individuals. Trainees will generally receive support for two years of investigation and will emphasize the application of basic techniques, cutting edge bioinformatics approaches, and rigorous clinical and epidemiologic methods to improve our understanding of the processes that underlie pediatric diseases and to develop new and effective therapies for children. Trainees will have access to the full array of clinical and laboratory research cores and will benefit from the extensive educational activities at CHOP and Penn, including master degree programs, individual courses, journal clubs, and a range of seminars. The Principal Investigator/Program Director and the Training Director will receive assistance from an internal advisory committee and an external advisory committee to select candidate trainees, to review the scholarly progress of trainees, and to ensure the optimal operation of the program. The renewal of this T32 program will continue the tradition established during the past 17 years of the program, capitalizing on the tremendous strengths of CHOP as an academic pediatric institution and Penn as a leading research university, with an outstanding pool of subspecialty fellows, a large number of talented mentors, and numerous cutting edge research programs. CHOP and Penn provide a comprehensive, resource-intense environment and a proven track record of training academic investigators in basic, translational, and clinical research.